“I expect him to have a big response,” Love said of James on Monday. “He’s always done it. Even before he came back to Cleveland and since I’ve been here he’s always responded big. .... He’s going to approach this game as one that he’s going to have to lead and bounce back.”

Even if James does have a big Game 2 Tuesday night in Boston, he’ll need some help — and the Cavaliers know it.

Love said he thought the Cavs were a “little soft” in the first half in Game 1. Getting tougher could mean a lineup change for the Cavaliers.

Coach Tyronn Lue acknowledged that he was at the least considering inserting Tristan Thompson into the lineup after Boston’s Al Horford had his way in Game 1, scoring 20 points on 8-of-10 shooting.

“It’s definitely something we have to weigh,” Lue said. “We weighed it before the series started, but we’d won seven out of eight and we weren’t going to adjust until someone beat us and we didn’t play well with that lineup and that got us to this point.”

Lue said numbers showed that in the last three years, out of all the players that have guarded Horford over at least 30 possessions, Thompson is No. 1 in the league defending him.

Boston also outscored Cleveland 60-38 in the paint. That, JR Smith said, is a sign James’ supporting cast needs to do more.

“We’ve got to help ‘Bron,” he said. “We can’t just expect him to do everything. As role players, we’ve got to play our role.”

Thompson came off the bench Sunday but has fared well opposite Horford in the past. Change would mean going away from the three-guard lineup of Smith, George Hill and Kyle Korver, along with James and Love. That lineup tormented the Raptors last series.

Thompson said the Cavs weren’t able to “clean up the boo-boo on our lips” after the Celtics’ initial run in Game 1.

“I think as a team, 1 through 5, we gotta all play tougher,” Thompson said. “Obviously, when I check in the game I try to bring that toughness and that energy. But our starters gotta be ready to throw the first punch. We need them to do that, we need them to be physical and set a tone early.”

He said his past playoff success against Horford has come by him being himself, which means being active early.

“Horford is playing very well right now and he’s shooting the crap out of the ball,” Thompson said. “When I go check into the game, whether it’s him or (Aron) Baynes I just try to run the floor, set pick-and-rolls and just try to work him on both ends so that hopefully by the second half his legs might be a little tired where he might not make that three that he makes in the first half.”

The Celtics feel they are a much different team than the one that trudged into last year’s conference finals matchup with Cleveland still toting the emotional baggage of helping teammate Isaiah Thomas cope with the death of his sister.

Boston also started that series on just a days’ rest following a draining seven-game series with Washington.

None of that is a factor this time around for a rebuilt roster that despite being down two All-Stars in Kyrie Irving and Gordon Hayward, has found a synergy with its remaining group.

This incarnation of the Celtics is not only young and athletic but playing with a physicality that was missing at times last season.

The Celtics’ starters scored 88 points in Game 1, while shooting 58 percent from the field and going 10 of 21 from the 3-point line. Cleveland’s starters scored 46 points, shooting 33 percent from the field and going just 3 of 19 from beyond the arc.

“We got a lot of guys where we just don’t care,” Marcus Smart said. “(Cleveland is) here for a reason, because of the talent that they have. But we have talent as well.

“We have guys that are fearless. So we just go out there and do what we do.”